Rotor for axial-flow fluid machine



Aug. 1962 N. H. KENT ETAL 3,051,436

ROTOR FOR AXIAL-FLOW FLUID MACHINE Filed Feb. 10, 1960 Unite States Pater 3,051,436 Fatented Aug. 28, 1962 3,051,436 ROTOR FGR AXIAL-FLOW FLUID MACHINE Nelson Hector Kent and Thomas Steel, Derby, England, assignors to Rolls-Royce Limited, Derby, England, a company of Great Britain Filed Feb. 10, 1960, Ser. No. 7,869 Claims priority, application Great Britain Feb. 5, 1960 3 Claims. (Cl. 253-39) This invention comprises improvements in or relating to rotors for axial-flow fluid machines. One example of such a machine is a multi-stage axial-flow compressor as is employed in gas-turbine engines.

A rotor of an axial-flow fluid machine usually comprises a central shaft and a separate structure mounted on the shaft for carrying blades of the rotor.

According to the present invention, a rotor for an axialflow fluid machine comprises a hollow central torquecarrying member having formed in one piece with it outwardly-extending flange means to which the blades of the rotor are directly attached.

According to a feature of this invention, the rotor may comprise a plurality of such hollow torque-carrying members arranged end to end in axial alignment. The members may be butt-Welded together or may be provided with abutting bolting flanges. Preferably each such member has in one piece with it flange means for a single stage of rotor blading.

The arrangement of the manufacture and assembly.

One construction of rotor embodying the above and other features of invention is illustrated in the accompanying drawing.

The drawing shows the inlet end of a rotor for a multistage axial-flow compressor suitable for a gas turbine engme.

The rotor comprises a first hollow torque-carrying member having formed in one piece with it a series of four axially-spaced radial flanges 11, a bolting flange 13, and a stub shaft extension 14 for engaging a front bearing. The flanges 11 have aligned bores in them to receive pivot pins 12 which pivotally attach first stage rotor blades 15 to the member 10, the pins 12 passing through lugs 16 on the root ends of the blades 15.

The rotor also comprises second and third hollow torque-carrying members 17, 18 respectively which are of the same general diameter and are secured together in axial alignment over a butt-welded joint 19. The member 17 has a bolting flange 20 at its upstream end to abut flange 13 and to receive a ring of bolts 21 holding the member 10 in axial alignment with the members 17, 18. The member 18 has a bolting flange 22 at its downstream end to receive bolts 23 for attaching the members 10, 17, 18 to a further part 23 of the rotor. The part 23 may be constructed for blade-carrying in accordance with the invention or may be of any other convenient or conventional construction.

The member 17 has in one piece with it between its ends a series of axially-spaced radially-extending annular flanges 24 to which the second stage rotor blades 25 are attached in the same manner as described for blades 15.

The member 18 has in one piece with it between its ends a radially-extending annular flange 26 which has an invention has advantages in axially-thickened portion 26a at its periphery and a series of axially-spaced radially-extending annular flanges 27 are provided externally of the thickened portion 26a. Third stage rotor blades 28 are pivotally attached to the flanges 27 in the same way as described for the blades 15, 25.

The end flanges of the groups of flanges 11, 24, 27 may be provided with axial extensions for co-operating with stationary structure of the compressor to provide labyrinth type seals. For instance in the illustrated construction the downstream flange of each group has an axiallyprojecting annular extension 29 formed with annular ribs 30 co-oper-ating with stationary parts 31 carried at the inner ends of stator blades 32 of the compressor.

The pivot pins 12 are retained in position by circular spring rings 33 snapped into grooves in the end flanges of each group.

It will be seen that each of the hollow torque-carrying members 10, 17, 18 is of tubular form and has a relatively thin wall thickness and further, that the internal diameter of each is large compared with the wall thickness. It will also be seen that the blade-carrying flanges 11, 24 and 26 have a radial extent which is small compared with the internal diameter of the respective torquecarrying member '10, 17, 18. As a result the compressor rotor has a very much lighter weight than known constructions of compressor rotor in which each ring of blades is carried by a separate radially extensive disc. The members 10, 17 and 18 are also relatively simple and cheap to manufacture as compared with known arrangements as just described.

We claim:

1. A bladed rotor according to claim 3, having some at least of the tubular members butt-welded together.

2. A bladed rotor according to claim 1, having some at least of the members provided with abutting bolting flanges, there being bolts extending through the flanges to secure the members in axial alignment.

3. A rotor for an axial-flow fluid machine comprising a plurality of tubular members secured together end to end to provide a hollow torque-carrying structure of the rotor, the tubular members having a radial wall thickness which is small and an internal diameter which is large compared with the wall thickness, and each tubular member having in one piece with it and extending radially outwards from it between its ends radial external flange means the radial extent of which is substantially smaller than the internal diameter of the tubular member, each said tubular member having a smooth internal bore extending axially from one end thereof to beyond said external flange means, and a series of rings of blades, each ring of blades being mounted on a corresponding one of the tubular members, each blade in a ring having a root portion directly attached to the radial flange means.

References Cited in the file of this patent UNITED STATES PATENTS 2,200,287 Lysholm May 14, 1940 2,317,092 Allen Apr. 20, 1943 2,440,933 Cunningham May 4, 1948 2,711,631 Willgoos June 28, 1955 2,747,367 Savin May 29, 1956 2,751,189 Ledwith June 19, 1956 2,918,252 Haworth Dec. 22, 1959 2,922,620 Shapiro J an. 26, 1960 

